add mouse movement observer

src/record/index.ts

@@ -60,6 +60,16 @@ function record(options: recordOptions) {
               },
             }),
           ),
+        mousemoveCb: positions =>
+          emit(
+            wrapEvent({
+              type: EventType.IncrementalSnapshot,
+              data: {
+                source: IncrementalSource.MouseMove,
+                positions,
+              },
+            }),
+          ),
       });
     });
   } catch (error) {

src/record/observer.ts

@@ -1,5 +1,5 @@
 import { INode } from 'rrweb-snapshot';
-import { mirror } from '../utils';
+import { mirror, throttle } from '../utils';
 import {
   mutationCallBack,
   textMutation,
@@ -7,6 +7,8 @@ import {
   removedNodeMutation,
   addedNodeMutation,
   observerParam,
+  mousemoveCallBack,
+  mousePosition,
 } from '../types';
 
 function initMutationObserver(cb: mutationCallBack): MutationObserver {
@@ -99,9 +101,49 @@ function initMutationObserver(cb: mutationCallBack): MutationObserver {
   return observer;
 }
 
-export default function initObservers(o: observerParam) {
-  const mutationObserver = initMutationObserver(o.mutationCb);
-  return {
-    mutationObserver,
+function initMousemoveObserver(cb: mousemoveCallBack): () => void {
+  let positions: mousePosition[] = [];
+  let timeBaseline: number | null;
+  const wrappedCb = throttle(() => {
+    const totalOffset = Date.now() - timeBaseline!;
+    cb(
+      positions.map(p => {
+        p.timeOffset -= totalOffset;
+        return p;
+      }),
+    );
+    positions = [];
+    timeBaseline = null;
+  }, 500);
+  const updatePosition = throttle<MouseEvent>(
+    evt => {
+      const { clientX, clientY } = evt;
+      if (!timeBaseline) {
+        timeBaseline = Date.now();
+      }
+      positions.push({
+        x: clientX,
+        y: clientY,
+        timeOffset: Date.now() - timeBaseline,
+      });
+      wrappedCb();
+    },
+    20,
+    {
+      trailing: false,
+    },
+  );
+  document.addEventListener('mousemove', updatePosition);
+  return () => {
+    document.removeEventListener('mousemove', updatePosition);
+  };
+}
+
+export default function initObservers(o: observerParam) {
+  const mutationObserver = initMutationObserver(o.mutationCb);
+  const mousemoveHandler = initMousemoveObserver(o.mousemoveCb);
+  return {
+    mutationObserver,
+    mousemoveHandler,
   };
 }

src/types.ts

@@ -26,20 +26,26 @@ export type fullSnapshotEvent = {
   };
 };
 
-export enum IncrementalSource {
-  Mutation,
-}
-
 export type incrementalSnapshotEvent = {
   type: EventType.IncrementalSnapshot;
   data: incrementalData;
 };
 
+export enum IncrementalSource {
+  Mutation,
+  MouseMove,
+}
+
 export type mutationData = {
   source: IncrementalSource.Mutation;
 } & mutationCallbackParam;
 
-export type incrementalData = mutationData;
+export type mousemoveData = {
+  source: IncrementalSource.MouseMove;
+  positions: mousePosition[];
+};
+
+export type incrementalData = mutationData | mousemoveData;
 
 export type event =
   | domContentLoadedEvent
@@ -57,6 +63,7 @@ export type recordOptions = {
 
 export type observerParam = {
   mutationCb: mutationCallBack;
+  mousemoveCb: mousemoveCallBack;
 };
 
 export type textMutation = {
@@ -92,8 +99,21 @@ type mutationCallbackParam = {
 
 export type mutationCallBack = (m: mutationCallbackParam) => void;
 
+export type mousemoveCallBack = (m: mousePosition[]) => void;
+
+export type mousePosition = {
+  x: number;
+  y: number;
+  timeOffset: number;
+};
+
 export type Mirror = {
   map: idNodeMap;
   getId: (n: INode) => number;
   getNode: (id: number) => INode;
 };
+
+export type throttleOptions = {
+  leading?: boolean;
+  trailing?: boolean;
+};

src/utils.ts

@@ -1,4 +1,4 @@
-import { Mirror } from './types';
+import { Mirror, throttleOptions } from './types';
 
 export const mirror: Mirror = {
   map: {},
@@ -9,3 +9,37 @@ export const mirror: Mirror = {
     return mirror.map[id];
   },
 };
+
+// copy from underscore
+export function throttle<T>(
+  func: (arg: T) => void,
+  wait: number,
+  options: throttleOptions = {},
+) {
+  let timeout: number | null = null;
+  let previous = 0;
+  // tslint:disable-next-line: only-arrow-functions
+  return function() {
+    let now = Date.now();
+    if (!previous && options.leading === false) {
+      previous = now;
+    }
+    let remaining = wait - (now - previous);
+    let context = this;
+    let args = arguments;
+    if (remaining <= 0 || remaining > wait) {
+      if (timeout) {
+        clearTimeout(timeout);
+        timeout = null;
+      }
+      previous = now;
+      func.apply(context, args);
+    } else if (!timeout && options.trailing !== false) {
+      timeout = setTimeout(() => {
+        previous = options.leading === false ? 0 : Date.now();
+        timeout = null;
+        func.apply(context, args);
+      }, remaining);
+    }
+  };
+}